Proportion Calculator
This proportion calculator helps you find a missing value in a proportion of the form A/B = C/D. It’s useful for solving mathematical problems involving ratios, scaling, or cross-multiplication. Just input three known values, and the calculator will compute the fourth.
Proportion Calculator
Proportion Formula
$$\frac{A}{B} = \frac{C}{D} \quad \Rightarrow \quad D = \frac{B \cdot C}{A}$$
To find the missing value in a proportion, use the cross-multiplication rule. Multiply the means and divide by the known extreme to solve for the unknown.
Proportions are used in mathematics, physics, finance, and everyday situations to express equality between two ratios.
For example, if a map uses a 1:1000 scale, or a recipe is doubled, proportions ensure accurate scaling. Given any three values in the ratio $$A/B = C/D$$, the fourth can be calculated using the formula. This tool simplifies solving proportions by eliminating manual calculations and reducing errors.